Amphoteric surfactants are those which contain both an anionic and a cationic hydrophilic group within the same molecule. Therefore these surfactants have both anionic and cationic functionalities. Typically the cationic portion is a quaternary ammonium derivative while the anionic portion can be a carboxylate, sulfonate or sulfate group.
Prior art listed below describes amphoteric surfactants containing one or more synthetic features of the present invention. Many employ dimethylaminopropylamine, and some use hydrophobic epoxides. Most contain sodium chloride as a co-product.
a. A well-known amphoteric surfactant, generically named cocoamido betaine, is prepared from dimethylaminopropylamine, coconut fatty acid, and sodium chloroacetate: ##STR1##
Some trade names for this material are MIRATAINE.RTM. (Miranol Chemical Co.), LONZAINE.RTM. (Lonza, Inc.), TEGO BETAINE.RTM. (Goldschmidt Chemical Corp.) and MONATERIC.RTM. (Mona Industries). All contain sodium chloride. One of these betaine products, MIRATAINE CB.RTM. was used as a standard lime soap dispersing agent in Examples II-B and IV-B. The lime soap dispersion of the betaine of the present invention in Example I-B was superior and that in Example III-B was slightly inferior to the MIRATAINE.RTM..
b. Other common amphoterics include alkylaminopropionic acids such as DERIPHAT.RTM. (Henkel Corp.): EQU R--N[(CH.sub.2).sub.2 CO.sub.2 H].sub.2
Texaco Chemical Company's Experimental Surfactant MA-300 is of this type: ##STR2##
Patents describing other structures include:
______________________________________ c. U.S. Pat. Nos. 4,076,743 4,139,553 4,148,762 ##STR3## ______________________________________
These structures are prepared from olefin epoxides and dimethylaminopropylamine. The carboxylate group is introduced by reaction with sodium chloroacetate to form the quaternary ammonium group. Sodium chloride is a co-product of the betaine.
______________________________________ d. U.S. Pat. Nos. 4,076,744 4,192,817 ##STR4## ______________________________________
This polyanionic surfactant is prepared from N-alkyl diethylenetriamine, maleic anhydride, sodium chloroacetate and sodium sulfite. Since it contains no quaternary ammonium groups, its amphoteric behavior is pH dependent.
______________________________________ e. U.S. Pat. No. 4,180,468 ##STR5## ______________________________________
This material is made from 1-hydroxyethyl-2-alkylimidazoline, sodium hydroxide and ethyl acrylate. A similar structure is derived from the same imidazoline and alkaline sodium chloroacetate:
______________________________________ U.S. Pat. No. 4,304,932 ##STR6## f. U.S. Pat. No. 4,214,102 ##STR7## ______________________________________
Alkyl glycidyl ether, aminoethylethanolamine and sodium chloroacetate are used to prepare this surfactant. Like the structures shown for (b), (d), and (e), this material has no quaternary nitrogen, so its cationic character is apparent only at low pH.
Amphoteric surfactants find utility in a wide number of applications including the textile industry, metal cleaning, industrial cleaning applications, foaming applications as well as cosmetics and health and beauty aides.